1. Field of the Invention
The present invention relates to a clear antiperspirant and/or deodorant gel composition for application to the skin. More particularly, the present invention relates to a gel composition that exhibits a soft feel to the skin when applied. Still more particularly, the present invention relates to a gel composition that provides a high degree of antiperspirant efficacy. It is believed that this gel composition has improved aesthetics and performance due, among other things, to its viscosity that is between about 7,000 centipoise (cps) to about 25,000 cps at 25 degrees C.
2. Description of the Prior Art
Antiperspirant/deodorant compositions are commonly applied to the skin at the underarms to prevent or alleviate sweating and/or odor. Such compositions take a variety of physical forms such as a stick, gel, cream, roll-on liquid, pump spray and aerosol spray.
A popular form of an antiperspirant/deodorant composition is the gel. Gels can be made transparent (clear), translucent, or opaque. Clear gel compositions are particularly aesthetically pleasing to consumers. Conventional clear gel compositions typically take the form of water-in-silicone emulsions with an antiperspirant active.
A problem commonly encountered with antiperspirant/deodorant gel compositions is stiffness. When a gel composition is stiff, it does not spread easily on the skin. When applied by a user, coverage on the skin may be non-uniform. Non-uniformity of coverage reduces the evaporation rate of volatiles, which can cause a tacky or sticky feel on the skin. Also, the gel composition may be slow to dry.
The prior art sets forth 3 variety of antiperspirant/deodorant compositions. They include those disclosed in U.S. Pat. Nos. 4,122,029; 4,268,499; 4,363,988; 4,673,570; 4,719,103; 4,725,431; 4,782,095; 4,944,938; 4,948,938; 5,162,378; 5,393,518; 5,449,511; 5,492,691; 5,520,907; 5,587,153; 5,925,338; 5,939,055 and 6,063,365.
U.S. Pat. No. 4,673,570 relates to clear gel compositions having a silicone emulsifier with a viscosity of 600 centipoise (cps) to 2,000 cps. U.S. Pat. No. 5,393,518 provides an antiperspirant composition having cyclomethicone, aluminum zirconium tetrahydrochoride and dimethicone copolyol, with a viscosity less than 1,000 cps. U.S. Pat. No. 5,587,153 relates to clear gel compositions in the form of a water in silicone emulsion. The composition has a viscosity of 50,000 cps to 200,000 cps, a clarity of 50 nephelomedric turbidity units (NTU) or less, and a refractive index of 1.3975 to 1.4025. U.S. Pat. No. 5,925,338 relates to gel compositions in the form of water-in-silicone emulsions of a viscosity of 50,000 cps to 250,000 cps.
U.S. Pat. No. 5,449,511 is directed to anhydrous, solid antiperspirant compositions having 48.1% cyclomethicone, 22.7% aluminum zirconium tetrahydrochoride and 5% dimethicone copolyol.
U.S. Pat. No. 6,063,365 provides a gel composition having aluminum chlorohydrate, dimethicone, cyclomethicone, dimethicone copolyol, and water.
The gel compositions of the prior art are too stiff to effectively apply uniformly to the skin to enhance antiperspirant/deodorant efficacy. It would be desirable to have a gel composition that could be applied uniformly.
It would further be desirable to have a gel composition that provided enhanced antiperspirant activity. The prior art has discussed the use of formaldehyde as an antiperspirant active. U.S. Pat. No. 4,263,274 provides that formaldehyde has anhydrotic properties but is not useful due to strong odor, irritating effects on the skin and/or high skin permeability or skin staining. U.S. Pat. No. 5,508,024 provides that aldehydes, such as formaldehyde, can suppress sweating but that their sensitization potential has prevented commercialization. Antiperspirants and Deodorants, Marcel Dekker, p.108-109, (1988) points out that formaldehyde is an effective antiperspirant but that it has not been commercialized due to its sensitizing capability. U.S. Pat. No. 4,605,554 provides roll-on liquid or powder antiperspirant/deodorant compositions. Formaldehyde donors are disclosed as deodorant chemicals. No antiperspirant activity is disclosed.
It would be desirable to have an antiperspirant/deodorant gel composition that delivers formaldehyde as an antiperspirant active. It would be desirable to have such a gel composition that delivers formaldehyde without undue skin sensitization.
It is an object of the present invention to provide a gel composition that affords excellent antiperspirant and/or deodorant protection from bodily sweating and/or odor.
It is another object of the present invention to provide such a gel composition that is substantially clear and aesthetically appealing.
It is a further object of the present invention to provide such a gel composition that is soft to the touch yet provides excellent coverage and physical integrity at the surface of the skin, particularly the underarms.
It is still a further object of the present invention to provide a method of decreasing perspiration from human skin comprising applying to the skin the clear antiperspirant/deodorant gel composition described above.
These and further objects and advantages of the present invention are achieved by a clear antiperspirant/deodorant gel composition that takes the form of a water-in-oil emulsion having a viscosity of about 7,000 cps to about 25,000 cps.
The gel composition may also include a formaldehyde donor as an antiperspirant active or as an antiperspirant enhancer, and may deliver such formaldehyde donor in a manner that the skin is substantially not sensitized or irritated.
It was surprising that an antiperspirant/deodorant gel composition could be formulated that could be easily and uniformly spread on the skin, yet dry quickly. It was also surprising that such gel composition could be formulated to feel soft and provide excellent antiperspirant activity. It was still further surprising that such gel composition could be formulated to appear clear and aesthetically pleasing.
The gel composition of the present invention takes the form of a water-in-oil emulsion, preferably a water-in-silicone emulsion. The composition has a viscosity from about 7,000 centipoise (cps) to about 25,000 cps. Also, the composition preferably exhibits a clarity from about 30 NTU or less. The gel composition further has about 5 percentage by weight (wt. %) to about 50 wt. % of an antiperspirant active, about 25 wt. % to about 45 wt. % water, about 0.1 wt. % or more of a silicone gelling agent, and about 9.0 wt. % or more of one or more silicone oils, based upon the total weight of the composition.
An important aspect of the present invention is the viscosity of the gel composition. Viscosity of the gel composition is important in imparting desired physical properties and feel to the skin. If viscosity is too high, the gel composition is too stiff and may be difficult to spread uniformly on the skin. Non-uniform application decreases efficacy and increases the amount of time required for volatiles to evaporate. Slow evaporation results in longer drying time. In general, high viscosity can result in the gel composition feeling wet and sticky to the consumer for an unacceptably long period of time. If viscosity is too low, the gel composition will feel wet and sticky to the user for an even unacceptably longer period of time, probably due to a very high oil content.
In the present invention, it has been discovered that a gel composition having a viscosity range from about 7,000 cps to about 30,000 cps, preferably to about 25,000 cps, more preferably from about 12,000 cps to about 21,000 cps, and most preferably from about 18,000 cps to about 21,000 cps, provides significantly improved physical properties and characteristics. Such viscosity is low enough to facilitate excellent spreading and uniform coverage on the skin, yet is high enough to avoid an excessive oil content.
The present gel composition has an antiperspirant active to reduce body sweating and, consequently, odor. Preferably, the antiperspirant active is present in the gel composition from about 5 wt. % to about 50 wt. %, based on the total weight of the composition. More preferably, the antiperspirant active is present from about 15 wt. % to about 25 wt. %, based on the total weight of the composition. Antiperspirant actives that can be used in the present composition include, but are not limited to, aluminum chlorohydrate; aluminum zirconium trichlorohydrate, tetrachlorohydrate, pentachlorohydrate, and octachlorohydrate; aluminum zirconium trichlorohydrex-gly, tetrachloroydrex-gly, and pentachlorohydrex-gly, and octachlorohydrex-gly; and calcium chloride and other metal halide salts capable of reducing body sweating.
The present invention preferably includes in the gel composition a substantial amount of water. The amount of water may range from about 25 wt. % to about 45 wt. % of the total weight of the composition. The relatively high water content enables the proportion of glycols and silicone oils in the gel composition to be reduced. In addition to saving on ingredient cost, namely less of the more expensive glycol versus water, the reduced glycol content facilitates the evaporation of the volatile silicone and the water.
It was very surprising to find that the composition of the present invention was able to comprise a relatively high amount of water, yet have excellent physical integrity of the gel, feel soft to the touch, be substantially transparent, apply uniformly, and have improved antiperspirant efficacy.
The present gel composition also has a silicone emulsifier that acts as a gelling agent and one or more volatile and/or non-volatile silicone oils. Silicone gelling agents provide a gel matrix and bulk for the gel composition. The gelling agents act as emulsifiers in forming the water into silicone emulsions or gels. The silicone oils function to thicken and soften the gel composition and provide softening and conditioning effects to the skin.
The silicone gelling agent is present in the gel composition at about 0.1 wt. % or more, and preferably about 0.5 wt. % to about 5.0 wt. %, based on the total weight of the composition. More preferably, the silicone gelling agent is about 0.5 wt. % to about 1.5 wt. %, based on the total weight of the composition.
Silicone gelling agents that can be used in the composition of the present invention include, but are not limited to, dimethicone copolyol (polyether substituted dimethicone), laurylmethicone copolyol, cetyl dimethicone copolyol and stearyl dimethicone copolyol. Dimethicone copolyol is described in U.S. Pat. No. 4,122,029, which is incorporated herein by reference. The preferred silicone gelling agent, dimethicone copolyol, is a mixture of 10% dimethicone copolyol and 90% cyclomethicone. The former acts as a gelling agent, while the latter acts as a solvent.
The silicone oils used in the present composition typically have boiling points below about 250xc2x0 C.
Such silicone oils include volatile silicone oils, such as cyclomethicone (pentamer is preferred; tetramer; hexamer; and mixtures thereof) and dimethicone having a viscosity of about 0.65 to about 2 centistokes. Non-volatile silicone oils that can be used in the present composition include high molecular weight polysiloxanes, high viscosity linear dimethicones, namely from about 5 to about 100,000 ceritistokes, phenyl trimethicone cetyl dimethicone and stearyl dimethicone. The preferred range for the silicone oil is from about 9 wt % to about 30 wt %, based on the total weight of the composition.
A preferred combination of a volatile silicone oil and a silicone gelling agent is a cyclometriicone/dimethicone copolyol blend. This blend is sold commercially as DC 5225C and DC 3225C by Dow Corning Corporation as a 90/10 by weight blend. The blend is also commercially available under the trade names SF 1528 from General Electric Silicones.
The gel composition may have non-silicone co-gelling agents or thickeners, if desired. Such co-gelling agents include: cellulose derivatives, such as carboxymethylcellulose, methylcellulose, hydroxypropylmethylcellulose and hydroxyethylcellulose; carrageenan gum; xanthan gum; tragacanth gum; caraya gum; gum arabic; polysodium acrylate; and, polyvinyl pyrrolidone. A preferred co-gelling agent is a cationic hydroxyethyl cellulose. The preferred cationic hydroxyethyl cellulose is Polyquaternium-10, and is sold by National Starch. The co-gelling agent may be used together with or in place of the silicone gelling agent.
The emulsion of the present gel composition can be formulated with any emulsifier or surfactant known in the art as useful in water-in-oil emulsions. Such emulsifiers and surfactants that can be used in the present invention include, but are not limited to, Steareth-2, Steareth-20, PPG 5-Ceteth-20 and POE (20M) Sorbitan Monolaurate. Additional useful emulsifiers, co-emulsifiers, and surfactants are provided in U.S. Pat. No. 5,162,378 (column 4), which is incorporated herein by reference.
The present gel composition may be formulated to exhibit a high degree of clarity by means known to those skilled in the art. Clarity can be characterized on the basis of turbidity and/or index of refraction.
The present gel composition preferably exhibits clarity from about 5 nephelomedric turbidity units (NTU) to about 30 NTU, and more preferably about 10 NTU to about 20 NTU. The present gel composition also preferably exhibits an index of refraction from about 1.39 to about 1.41, and preferably 1.399 to 1.405. Refractive index modifiers can be added to either or both of the oil or water phases to modify index of refraction. Preferably, the oil and water phases of the gel composition exhibit indices of refraction within 0.0004 of each other to provide a preferred level of overall clarity to the composition.
Representative refractive index modifiers together with their respective indices of refraction are listed in the Table below. The listing also includes colorants, which may be added to gel compositions to modify refractive index, mask off colors of antiperspirant actives or other ingredients, or provide a desired product color for aesthetic appeal. The listing is representative and not to be construed as limiting.
Both turbidity and refractive index impact the overall clarity of the present composition, but do not account for the improved aesthetic feel of the composition on one""s skin.
In a preferred embodiment, the gel composition has a formaldehyde donor therein. The formaldehyde donor functions both as a preservative and as an antiperspirant in the gel composition. Formaldehyde donors are known in the cosmetic and personal care product art as being useful in preservative or antimicrobial applications. However, heretofore they have not been appreciated as commercially practical antiperspirant actives. In the present invention, it was unexpectedly found that formaldehyde donors exhibited significant antiperspirant activity in a gel composition. The gradual release of formaldehyde by the donors permits bodily sweating to be reduced while substantially avoiding the skin sensitization problems normally encountered when significant amounts of formaldehyde are directly utilized in the composition.
Formaldehyde donors useful in the present invention include, but are not limited to, diazolidinyl urea, DMDM hydantoin, imidazolidinyl urea, Quaternium-15 (Dowicil 200) and a combination thereof. Formaldehyde donors can also serve as enhancers for conventional antiperspirant actives such as those described above in the present gel composition, or other product forms such as sticks, creams, emulsions, sprays and roll-ons.
It is understood that the present gel composition may optionally contain other ingredients, such as one or more analgesics, antibacterials, antlmicrobials, anti-allergenics, chelating agents, colorants, fragrances, lubricants, moisturizers, preservatives, skin protectants, stabilizers, sunscreens, surfactants, vitamins, and the like.